Safety switch for power tools

Abstract

A clutch safety switch of a power chainsaw includes a safety member slidably connected to the casing and a trigger which is not able to be squeezed when the safety member is not slid away. A gear connected to the power source has engaging recesses and a clutch device member is rotatably mounted to an output shaft which is independent from the gear. A link is connected between the safety member and a plate connected to the clutch member which is rotated to engage the output shaft with the gear by sliding the safety member. A lever is connected to the plate which is pivoted by pushing the lever to allow the link to move in a horizontal portion of an L-shaped slot in the plate to make the safety member be pushed back to disengage the clutch device from the gear to release the connection.

What is claimed is:  
     
       1. A safety switch for a power tool, comprising: 
       a casing having a slot defined therethrough and a safety member slidably engaged with said slot, a lug extending from an underside of said safety member, a trigger pivotally located in said casing and having a protrusion which is interfered by said lug of said safety member, a spring having one end thereof connected to said safety member and the other end of said spring connected to a stop member in said casing, a link having an end thereof connected to said safety member;  
       a gear received in said casing and adapted connected to a power source, said gear independently mounted to an output shaft and a plurality of engaging recess defined in said gear, a plurality of guide rods and guide members respectively extending from an inside of said casing;  
       a clutch member mounted to said output shaft and having a plurality of blades each of which has a guide slot in which respective one of said a plurality of guide rods extends, each blade having a tapered extension extending therefrom which is able to be movable along said guide member, an engaging member movably mounted to said output shaft and having bosses extending from a side thereof, a cover fixed on said clutch member and said engaging member being retained in a central hole in said clutch member by said cover;  
       one of said blades having a plate connected thereto and said plate having an L-shaped slot, the other end of said link engaged with said L-shaped slot in said plate, another spring having one end thereof connected to said plate and the other end of said another spring fixed to one of said plurality of guide rods in said casing, and  
       a lever pivotally connected to said casing and an extension connected to said lever, said extension having a first elongate slot and a second elongate slot, two pins extending from said inside of said casing and located in said first elongate slot, a position rod extending from said plate and movably engaged with said second elongate slot.  
     
     
       2. The safety switch as claimed in  claim 1 , wherein a frame located in said casing and has a tip portion extending therefrom, a plurality of notches defined in an underside of said extension and said tip portion engaged with one of said notches. 
     
     
       3. The safety switch as claimed in  claim 1 , wherein a spring has one end thereof connected to one of said blades and the other end of said spring is connected to one of said guide rods in said guide slot of one of the rest of said blades. 
     
     
       4. The safety switch as claimed in  claim 1 , wherein a plurality of rollers are embedded in said engaging member and said cover contacts said rollers. 
     
     
       5. The safety switch as claimed in  claim 1 , wherein a thumb portion extends from said safety member and through said slot.